Unless otherwise indicated herein, the materials described in this section are not prior art to the claims and are not admitted to be prior art by inclusion in this section.
A typical cellular wireless network includes a radio access network (RAN) having a number of base stations that radiate to define wireless coverage areas, such as cells and cell sectors, in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices, can operate. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks, such as the public switched telephone network (PSTN) and/or the Internet for instance. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs served by the base station.
In general, a cellular wireless network may operate in accordance with a particular air interface protocol or radio access technology, with communications from the base stations to UEs defining a downlink or forward link and communications from the UEs to the base stations defining an uplink or reverse link. Examples of existing air interface protocols include, without limitation, Orthogonal Frequency Division Multiple Access (OFDMA) (e.g., Long Term Evolution (LTE) or Wireless Interoperability for Microwave Access (WiMAX)), Code Division Multiple Access (CDMA) (e.g., 1×RTT and 1×EV-DO), Global System for Mobile Communication (GSM), WI-FI, and BLUETOOTH. Each protocol may define its own procedures for registration of UEs, initiation of communications, handoff between coverage areas, and functions related to air interface communication.
In accordance with the air interface protocol, each coverage area may operate on one or more carrier frequencies and may define a number of air interface channels for carrying information between the base station and UEs. These channels may be defined in various ways, such as through frequency division multiplexing, time division multiplexing, and/or code-division multiplexing for instance.
More specifically, a UE may register with a coverage area of the cellular wireless network by transmitting a registration request or attach request to the base station serving that coverage area. Once registered, the UE may then operate in an idle mode in which the UE monitors a downlink control channel to receive overhead information and to check for any page messages. Upon receiving a page message, the UE may be assigned traffic channel resources on which the UE may engage in air interface communication.
Unfortunately, however, although a number of base stations of a cellular network may radiate to define a number of wireless coverage areas and thereby provide vast wireless coverage on various carrier frequencies, cellular wireless networks may still have operational limitations. Due to, for example, limitations of bandwidth, frequency allocations, base station placement, processing power, or other considerations, each cell coverage area in a given cellular network may only effectively serve a limited number of UEs.
For example, a reverse link air interface may become overwhelmed if too many UEs being served by the coverage area seek to send access probes at once. As another example, a RAN may not have available traffic channels to assign/reserve for the number of UEs attempting communication. Regardless of the reasons for the heavy loads in the wireless coverage area, ultimately, heavy loads may result in delayed call setup and blocked calls, which may translate into unacceptable user experience.
Accordingly, one challenge of providing an effective cellular wireless network may be arranging cell coverage areas to balance competing needs: coverage areas (e.g., cells and sectors) should preferably not regularly encompass so many users that they often reach capacity, but they should preferably not encompass so few users that their resources are underutilized.